AdvancedNumeric answer
One hundred prisoners stand in a line, each wearing a black or white hat. Each sees every hat in front of them but not their own or those behind. Starting from the back, each calls out one colour, heard by all; those who name their own colour go free. With the best strategy agreed in advance, how many can be guaranteed to go free?
Answer with a number. Fractions, powers and expressions like 23/6 or C(52,5) are read correctly in practice.
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